The present invention relates to a method and composition for treating fibrous substrates, to thereby impart oil, water and soil repellency at substantially reduced add on levels of typical fluorochemical products useful in imparting those properties. Fluorochemicals are generally comprised of at least one fluorine containing resin and at least one non-fluorine containing resin which when co-applied to a fibrous substrate provide a durable film on the surface of the fibrous substrate the film may be either continuous or discontinuous in nature so as to cover all or part of the surface of the fibrous substrate.
In this disclosure it is of particular importance to distinguish the differences that exist between the terms A) soil repellency B) oil repellency and C) water repellency, as they relate to textiles.
A) Soil repellency refers to the ability of a fibrous substrate to resist the adhesion of dry soils. The tests performed to evaluate soiling performance levels generally involve applying standardized non liquid containing dry soil compositions to a fibrous substrate and further subjecting it to a moving load to simulate wear or trafficking and subsequently submitting the soiled substrate to a specified soil removal process, such as vacuuming. These tests may also involve water extracting. The substrate is then compared to a control sample or standard of established value. PA1 B) Oil repellency refers to the degree to which a substrate repels liquids of this type. Typically AATCC test method 118-1983 is used to determine oil repellency values from `1` to `8` where in `8` is the highest repellency rating. PA1 C) Water repellency refers to the degree to which a substrate repels water and water/isopropanol mixtures and is determined using a similar method to that for oil repellency. PA1 (a) 0.1 to 35 parts by weight of an aqueous colloidal sol dispersion containing from about 5% to about 26% by weight solid organosilsesquioxane co-polymers having units selected from the group consisting of R SiO.sub.3/2, R'.sub.2 SiO and R".sub.3 SiO.sub.1/2 units, wherein each R, R' and R" radical is selected from the group consisting of hydrocarbon and substituted hydrocarbon radicals containing from 1 to 7 carbon atoms, the co-polymers having an overall particle size range of from about 10 Angstroms to about 2000 Angstroms in a sufficient amount to yield from 0.04% to 0.32% solids based on the weight of the fibrous substrate to which it is applied; PA1 (b) from 0.00 to about 0.96 parts by weight of solids of fluorochemical resins selected from the group of liquids containing at least one dispersed or emulsified fluorine containing resin, added as an aqueous fluorochemical dispersion or emulsion wherein the fluorine content of the resin is from about 15% to 50% by weight in a sufficient amount to yield from about 100 parts per million to about 500 parts per million fluorine atom on the fibre; and PA1 (c) 64.04 parts to 99.9 parts by weight of a diluent, and then heating the fibrous material to cause curing of resin components so applied. PA1 a) enhanced soil repellency values or PA1 b) enhanced water repellency values or PA1 c) enhanced oil repellency values or PA1 d) any combination of a), b), or c) PA1 Emulsion PA1 Sold by 3M Specialty Chemical Division. PA1 Approximately 41% solids PA1 Approximately 59% medium PA1 Sold by Daikin Industries Ltd. PA1 Approximately 30% solids PA1 Approximately 70% medium PA1 Sold by Advanced Polymers Inc. PA1 Approximately 30% solids PA1 Approximately 70% medium PA1 Sold by Advanced Polymers, Inc. PA1 Approximately 22% solids PA1 Approximately 78% medium PA1 Sold by Advanced Polymers, Inc. PA1 Approximately 30% solids PA1 Approximately 70% medium PA1 Sold by 3M Specialty Chemicals Division PA1 Sold by 3M Specialty Chemicals Division PA1 Sold by 3M Speciality Chemicals Division PA1 Sold by Hydrolabs Inc. PA1 Phenolic Resin PA1 Sold by Dupont Flooring Systems
The extensive and preferred application of fluorochemicals to provide fibrous substrates with water, oil and soil repellency has led to the use of oil and water repellency values to be deemed directly proportional to soil repellency values and this is often not true.
The significance of each type of repellency value is for example, directly related to the type of repellency required for a particular textile end use. An awning type material that is exposed to the elements will derive maximum benefit from a high level of water repellency and a low to no oil repellency level but to maintain an acceptable appearance it should be provided with high soil repellency. Surgical gowns, masks and other such clothing, which are for the most part disposable, require high levels of oil and water repellency to prevent liquid penetration but require little if any soil repellency. Carpeting on the other hand requires moderate levels of oil and water repellency to fend off occasional spills but requires the highest level possible of soil repellency to promote effective and easy maintenance.
The diverse end use requirements for oil, water and soil repellency has led to a wide variety of fluorochemicals being developed. They provide a wide variation in the type of protection and levels of protection offered. It is therefore of major benefit to have a range of fluorochemical products which at point of application to a fibrous substrate can be provided with admixture components and process parameters that will reduce by up to 60% the quantity of fluorochemicals required to obtain certain specified levels of oil, water, and soil repellency.
It is the focus of this disclosure to provide a method and compositions for treating fibrous substrates whereby the amount of fluorochemicals required may be reduced by up to 60% while maintaining specified levels of repellency for a given fibrous substrate.
Processes have already been described such as in Canadian Patents Nos. 832,401 of Bey issued Jan. 20, 1970 and 830,886 of Mohrlok et al issued Dec. 30, 1969 and German published specification DE-OS No. 1,594,985 for treating fibrous substrates to render them repellent to dry soil by applying thereto a colloidal suspension of silsesquioxanes which consist of R SiO.sub.3/2 units and have a particle size of 10 to 1,000 Angstroms.
U.S. Pat. No. 4,351,736 of Steinberger et al issued September 28, 1982, further provides for a textile impregnating agent useful for pile stabilization and a process for its preparation comprising a colloidal suspension of a silicic acid with SiO.sub.2 units and organosilsesquioxanes having units of the formula R SiO.sub.3/2 wherein R is an alkyl or aryl radical with up to 7 carbon atoms and an average particle size of about 200 to 500 Angstroms and wherein the solids range from about 2% to about 9% by weight. This U.S. patent also teaches that the same textile impregnating agent provides significantly higher levels of soil repellency than that provided by DE-OS No. 1,594,985 type agents.
U.S. Pat. No. 4,781,844 of Kortmann et al issued November 1, 1988, describes further use of colloidal suspensions of organosilsesquioxanes described in U.S. Pat. No. 4,351,736 by combining those colloidal suspensions in specific ratios with certain perfluoroalkyl group containing resins within a specified range of resin solids content, to provide a textile finishing agent which, when diluted in and applied to a textile substrate and dried at elevated temperature, results in improved oil, water and soil repellency, over and above that of the described fluorochemical resins when applied in the same weight percent to a fibrous substrate without the addition of the described organosilsesquioxanes. This patent makes no reference to the possibility of fluorochemical reduction, based on weight of the fibrous substrate, resulting from the application of the prepared fibrous substrate finishing agent comprised of certain specified materials, in fixed ratios of weight percent to one another.